Dear Soyinfo Center,

I wanted to introduce a tofu variety that I researched last summer in Guizhou, China, that I think is extremely distinctive and could have wide commercialization potential in the United States. In Chinese, it is called suantang doufu (酸汤豆腐), which literally translates to “sour soup tofu.” I think a better translation might be acid curded tofu, but since the food is rare outside of the region, it doesn’t have an established English name.

Unlike most tofu varieties that are curdled using neutral salts, this variety uses acid, traditionally the leftover juice from making Guizhou-style suancai (酸菜) or pickled vegetables. Tofu curds are pressed and processed into several different varieties (at least 10, but likely many more). Some of these varieties resemble salt curded tofus, but for others major functional and taste differences exist. Since Guizhou tofu is made through acid/base reactions, some cook up very differently. The most distinctive characteristics include an exploding juiciness and truly creamy curds (for certain varieties), and less-beany flavor.

Besides Guizhou, some other areas of China do have acid curded tofus, generally called suanjiang doufu (酸浆豆腐). One notable variety comes from Shaanxi Province and is called yulin doufu (榆林豆腐).

These non-Guizhou acid curded tofus are generally formed into standard tofu cakes, with no extra processing or differences in cooking preparation, compared to salt curded tofus. In contrast, many Guizhou tofus undergo significant alteration.

Below are a few main points on curding, tofu flavor, tofu types, special preparations, as well as a general overview. I’ll also include a brief about me, in case anyone wants to reach out independently.

About me:

My name is George Stiffman, and I research plant-based Chinese cuisine and tofu.

I studied Chinese and Business (consumer behavior and entrepreneurship) at the University of Southern California, and graduated in December 2019. Between semesters, I spent several summers working in Buddhist Chinese restaurant kitchens in Beijing and Xiamen. Before that, I attended culinary training programs in Tianjin, Xiamen, Guangzhou, and Chengdu. Throughout 8 months from winter to summer 2019, I split my time between studying business and international relations at Peking University and traversing the country, searching out unique plant-based foods and sub-cuisines buried within local eating traditions. That August, I began researching Guizhou-style tofu production, working at two shops in Guiyang that together produced 5 different varieties of tofu.

I’ve shared findings of my travels and research at Chinese plant-based industry conferences, as well as on my blog, msgisvegan.com, and Instagram, of the same name.

Nowadays, my main focus is on a cookbook called Broken Cuisine (www.brokencuisine.com), which is about incorporating Chinese tofus into western cooking.

If you want to learn more of what I’m up to, or inquire about partnerships, please shoot me an email at georgestiffman at gmail dot com.

General Overview:

Guizhou tofus are indisputably the most varied and distinctive tofus in China, but because of the province’s long-standing economic, topographical, linguistic, and cultural isolation, these foods are hardly known outside of it. (Throughout China, Guizhou’s neighboring province Yunnan is much better known for its tofu, in particular shiping doufu (石屏豆腐) and baojiang doufu (包浆豆腐). I assume this recognition comes mainly from tourism and the rapid nationwide expansion of Yunnan restaurant chains.)

grilled baojiang doufu with a chili oil dipping sauce

Guizhou tofus are generally made by hand in small family shops, operating out of produce markets. Many tofu producers come from families that have been making tofu for several generations. In some counties or villages, like bijiedafang (毕节大方) where my teacher is from, every home either produces tofu or Chinese white alcohol. Other areas of Guizhou that produce their own unique varieties of tofu include Qingyan (青岩) village and Zunyi (遵义) city.

Large-scale production is rare, likely because tofu sells for so cheap (not profitable) and the public demands hand-made, wood-smoked, or other factors that don’t scale easily. Tofu production is also looked down upon as an extremely difficult, time-consuming, low-class trade.

Curding:

Most tofu shops buy vegetable pickling juice from a nearby shop or make their own. It has a fermented, sour taste but is otherwise very neutral. They add this juice to hot soymilk similarly to how one would use salt coagulants. Ideally, the juice is added in three small additions over the course of 30+ minutes. Once curds have sufficiently coagulated, excess juice is removed, placed in a covered vat at room temperature, and reused for later batches of tofu. Every subsequent batch recycles these juices, increasing its flavor and complexity.

At the small factory where I worked, we would use one vat of recycled juices for up to one week, at which point it would start to become rancid (this was during the summer, indoor temp ~80oF). At that point, we would reserve just the juices from a new batch of tofu and start again, throwing out the old juices.

When I measured the pH of the juices, before and after curdling the tofu, the handheld device I used gave a reading of 6 — just slightly acidic. I think this reading was far too high (not acidic enough), and a sign that the device wasn’t working properly. Under normal circumstances, acid won’t fully curdle tofu until it reaches a pH of around 4.5. That said, the mineral content of the water used (both tap water and reused curdling juice) had a TDS dissolved mineral content of 380 — incredibly high. I suspect that this high dissolved mineral content also helped with the curdling.

One shop I visited used mostly acid to curdle their tofu but added a little lushui (卤水), or salt brine, at the very end. The salts they used are similar to other common tofu coagulants. The small factory I worked at used only acid, which I believe is the most common approach.

Where pickling juices are not available, you can instead use a neutral flavored acid (like white vinegar) as a starter. After 2–3 batches, the leftover juices will start building up more positive flavors. (The first few batches will not taste good.)

Tofu Flavor:

Interestingly, unprocessed acid curded tofu tastes slightly sweet. It has less of a beany-ness than many other types of tofu. Most of the remaining flavor, however, depends on how the tofu is processed, whether the soymilk was boiled using woodfire, coal, or gas; the mineral content of the water; if the pressed tofu was dusted or submerged in alkaline powder or solution; whether the tofu was smoked, dried, or fermented, etc.

Tofu types:

Like salt curded tofu, acid curded varieties can be processed into many different forms. Many look similar but cook and taste different. Others have no counterpart. Besides the ubiquitous standard tofu cakes, here are some other varieties:

1. shuidoufu (水豆腐) / douhua (豆花). Fresh, slightly pressed tofu curds.

This resembles a Sichuan-style douhua but is curded with acid. Once curds form, they are pressed together using the back side of slotted sieve until they stick together, slowly and over low heat.

2. caidoufu (菜豆腐). Vegetable in fresh tofu curds

Like the fresh tofu curds above, but with ripped cabbage or mustard greens added to the soymilk during curdling.

caidoufu (pronounced “tsai doh foo”)

3. dafang shousi doufu (大方手撕豆腐). Dafang (county) hand-ripped tofu

A variety of doufugan (豆腐干) or firmly pressed, dried tofu, originating in bijiedafang (毕节大方). This tofu is made from tougher curds (i.e. more acid added during curding), and after pressing to ~3–4mm thickness is dusted with salt and alkaline powder. To cook, it is generally grilled and then dipped in seasoned chili powder. Traditionally, it was eaten by ripping it between your hands — thus its name.

grilled dafang tofu, served with seasoned chili powder

4. baojiang xiaodoufu (爆浆小豆腐). Exploding juice small tofu

A variety of pressed tofu, ~3mm thick, dusted with salt, alkaline powder, and msg. It is very tender (made with tender curds). It is generally grilled for a short minute on either side (using oil to prevent sticking), after which it becomes very juicy. It is traditionally dipped in seasoned chili powder after being cooked.

exploding juice tofu

5. qiaohui doufu (荞灰豆腐). Buckwheat ash tofu.

One of the most unique varieties of Guizhou tofu. I’m not sure how it’s processed, but from my understanding, white tofu cakes are covered in ash from burnt buckwheat, placed out at room temperature for a couple hours, then smoked. These buckwheat ashes have alkaline properties, and thus impart new characteristics on the tofu. Luodian county (罗甸县) has one particularly special variety, that is dense, soft, and chewy. Great for stews.

6. Jinqian doufu (金钱豆腐). Tofu coins

This variety looks like a thin, round pancake. I think it’s processed/prepared griddle-style but can’t find information about it online. Maybe uses okara? It is also processed using buckwheat ashes.

large tofu coins

7. jiaobandoufupi / Paodoufu (脚板豆腐皮/泡豆腐). Puffed dried tofu sheets.

Two varieties of dried tofus, both specialties of Qingyan village outside of Guizhou’s provincial capital, Guiyang. If the flatter, firmer jiaobandoufupi is cooked in hot stones, it puffs up to become paodoufu. These tofus must be reconstituted with water to be used. Paodoufu has a texture slightly similar to dongdoufu (冻豆腐), a common type of tofu cake that is frozen and develops a spongy texture.

jiaobanpi
paodoufu

A couple varieties are similar in name and appearance to salt curded tofus, but because they taste substantially different, I will mention them here:

1. furu (腐乳). Fermented tofu

Guizhou style furu simply has a different taste from most salt cured furu. I suspect it results more from the slightly acidic chemical properties of the tofu than from seasonings. The varieties I tried had richer flavors, more reminiscent of American cheeses than any vegan cheeses I have tried in the U.S. If these fermentation processes were studied more systematically, what’s stopping these products from developing as much variation as cheeses?

2. yanxun doufu (烟熏豆腐). Smoked tofu.

This variety is similar to Sichuan xianggan (香干) but is texturally denser and has a richer smoky flavor.

Here are a few more varieties or subvarieties that I have heard of and seem special or unique, but that I have not tried or researched:

  1. wuchuan huidoufu (务川灰豆腐). Wuchuan County Ash tofu. (a subvariety of qiaohuidoufu). LINK
wuchuan charcoal tofu

2. yuankou fadoufu (远口发豆腐). Camellia Flower Tofu from Yuankou Village. LINK

A distinctive take on tofu puffs, slowly frying acid curded tofu for 3–5 minutes in locally produced camellia flower oil, or shanchayou (山茶油). The finished tofu is soaked in water quickly after frying.

yuankou camellia flower tofu

3. shangji doufupi (尚稽豆腐皮). Shangji Village Stinky Tofu. LINK

Shangji tofu that is sliced, rubbed with grass and buckwheat ash, placed on top of a cone-shaped bamboo net, dried over a slow-burning charcoal fire. The next day, soak in water to rehydrate, place in bundles on the cone-shaped bamboo net and cover with a cotton towel to preserve heat and moisture. Heat over a slow-burning charcoal fire for 2–3 days. The resulting tofu can be eaten as is, julienned and eaten cold, or rehydrated a second time and stir-fried.

shangji stinky tofu

4. jiangkou doufugan (江口豆腐干). Jiangkou County sun-dried tofu. LINK

jiangkou dried tofu

Special Preparations

Every variety mentioned above has its own special uses. Some varieties, such as dafang shousi doufu and baojiang xiaodoufu, are often served grilled or bbq’d, dipped afterwards in seasoned chili powder. Shuidoufu and caidoufu are often served with rice and burnt chili/chili oil dipping sauce (called douhuafan,豆花饭). Notably, some of the most distinctive Guizhou tofu preparations come from basic tofu cakes. In one common snack — called doufuyuanzi (豆腐圆子) — blocks of plain tofu are hand mushed with scallion, salt, msg and then fried. The resulting balls have more cohesion, chew, and elasticity than a standard fried tofu ball, less oiliness, and don’t need any additional egg or binders. Another common snack, by far my favorite, uses blocks of plain tofu that are sliced to 2/3–1 in. thick, soaked in alkaline water for 30 minutes, drained and placed out for one day, then grilled. Without adding oil or anything else during grilling, the tofu will begin to develop a firm golden crust, puff up, and then the inside curds, under intense heat and pressure, will explode and release a creamy juice unlike anything else I have ever tried. The curds become creamy like a fresh burrata cheese. These grilled tofu slices are sliced open, and a burnt chili sauce infused with the intense-flavored root spice called zheergen (折耳根) is placed inside. This snack in Chinese is called lian’ai doufuguo (恋爱豆腐果), which literally translates to “love affair tofu fruit.”

I can imagine that the juiciness and creaminess of Guizhou tofus could be useful in other applications, especially outside of Chinese cuisine.

Researching Chinese tofu @ www.brokencuisine.com | vegan Chinese food @ IG: msgisvegan